a tribe of Mesoamerican (Mexico) Indians who live on Tiburón Island in the Gulf of California and on the adjacent mainland in Sonora.
Their language seems to be related to the Yuman languages, and both are commonly assigned to the hypothetical Hokan super-stock. Early 21st-century population estimates indicate approximately 800 individuals in the tribe.

Although the Seri now engage in commercial fishing and farm labour, traditionally they lived by gathering, hunting, and fishing for such edibles as shellfish, turtles, pelicans, and cactus fruit. Their simple cane spears, hunting bows, pebble tools, and dwellings of poles and cacti earned them a reputation as being among the most primitive aboriginal groups of North America. They did, however, produce pottery, basketry, and boat-shaped rush rafts.

The Seri lived in mobile bands of not more than 50 individuals. There were no formal band leaders and no social units larger than the band. Shamans, or medicine men, whose powers derived from dreams and visions, were important.

After an unsuccessful missionization attempt in the 18th century, the Seri were little influenced by Spanish colonizers. Although their population has declined, they retain most of their aboriginal social and religious customs.